SDI Seminar

Speaker: Arif Merchant, Storage System Program, HP Labs

Date: March 5, 1999
Time: 11:00 am
Place: Wean Hall 4623

An analytic behavior model for disk drives with readahead caches and request reordering


Modern disk drives read-ahead data and reorder incoming requests in a workload-dependent fashion. This improves their performance, but makes simple analytical models of them inadequate for performance prediction, capacity planning, workload balancing, and so on. To address this problem we have developed a new analytic model for disk drives that do readahead and request reordering. We did so by developing performance models of the disk drive components (queues, caches, and the disk mechanism) and a workload transformation technique for composing them. Our model includes the effects of workload-specific parameters such as request size and spatial locality. The result is capable of predicting the behavior of a variety of real-world devices to within 15% across a variety of workloads and disk drives. This is joint work with Elizabeth Shriver and John Wilkes.


Arif Merchant is a member of the Storage Systems Program at Hewlett-Packard Labs. His interests are in modelling and performance analysis of computer systems, particularly, storage systems. He received his B. Tech. from the Indian Institute of Technology in Bombay in 1984 and his Ph.D. from Stanford University in 1991. He worked at the IBM T. J. Watson Research Laboratories and the NEC Computer and Communication Laboratories before joining Hewlett Packard in 1995.